JEE · Chemistry doubts
232 doubts found
When do I use ΔG = −nFE in Electrochemistry, and what does it mean?
free energy change from cell potential.
How is Organic Chemistry — Basic Concepts tested in JEE, and what should I focus on?
Prioritise the core ideas: Inductive effect, Resonance, Electrophiles and nucleophiles.
How do I revise Hydrocarbons quickly before the exam?
One-page summary of Saturation, Markovnikov's rule, Aromaticity, then timed previous-year questions.
I keep getting “van't Hoff factor (i)” questions wrong in Solutions & Colligative Properties. What's the trap?
ignoring dissociation, so predicting equal effects for salt and sugar.
What are the most common mistakes students make in The Solid State?
Thinking that amorphous solids have a sharp melting point, believing all solids are perfectly ordered, and assuming only metals conduct electricity
When do I use PV = nRT in States of Matter: Gases, and what does it mean?
ideal gas equation of state.
What are the most common mistakes students make in Coordination Compounds?
Counting ligands instead of donor atoms, ignoring the ligand‑field effect on colour, and assuming colour depends only on the metal ion.
What are the most common mistakes students make in Haloalkanes & Haloarenes?
The usual slips: expecting haloarenes to undergo nucleophilic substitution as easily as haloalkanes, assuming every haloalkane reacts by SN2, and thinking halogens on benzene are meta-directing.
What are the most common mistakes students make in Alcohols, Phenols & Ethers?
Phenols are more acidic than alcohols; alcohols are weakly acidic, not neutral; tertiary alcohols do not oxidize like primary or secondary alcohols.
What are the most common mistakes students make in Aldehydes, Ketones & Carboxylic Acids?
Aldehydes are more reactive than ketones in nucleophilic addition, carboxylic acids do not undergo simple nucleophilic addition, and carboxylic acids are stronger acids than phenols.
What are the most common mistakes students make in Amines & Biomolecules?
The usual slips: thinking aniline is more basic than ammonia, applying 3° > 2° > 1° basicity in water, and calling sucrose a reducing sugar.
When do I use Molarity = moles / volume(L) in Some Basic Concepts (Mole Concept), and what does it mean?
concentration of a solution.
How is Structure of Atom tested in JEE, and what should I focus on?
Prioritise the core ideas: Quantum numbers, Orbitals, Filling rules.
What is the difference between polar molecule and non-polar molecule?
A polar molecule has a net dipole (water); a non-polar one has none because its dipoles cancel (CO₂).
When do I use ΔH = ΔU + Δn_gRT in Chemical Thermodynamics, and what does it mean?
relating enthalpy and internal energy changes.
When do I use K_w = [H⁺][OH⁻] = 10⁻¹⁴ in Equilibrium, and what does it mean?
the ion-product of water at 25°C.